This meant most of the generic-ness of it had to go away, since our
type system doesn't quite support it yet. Hopefully someday...
This version has lots of memory management errors. My next commit will
hopefully fix these.
Currently it's only sequential, but it can do word frequency
counting. In an ideal world it would all be polymorphic, but that
pushes the limits of our type system right now. We can generalize it
later.